Mobile furnace and method of facilitating removal of material from workpieces

ABSTRACT

The mobile furnace for removing foreign material, such as coatings, from workpieces. The mobile furnace includes burners for heating a combustion chamber of the furnace, and a burner control for operating the burners. The furnace is mounted on a wheeled vehicle or the like for transport to a worksite.

[0001] This application is a divisional of co-pending application Ser.No. 09/640,704, filed Aug. 18, 2000, the entire contents of which arehereby incorporated by reference and for which priority is claimed under35 U.S.C. § 120.

FIELD OF THE INVENTION

[0002] The present invention relates to a mobile furnace forfacilitating the removal of foreign material, such as coatings, fromworkpieces, and a method of facilitating the removal of foreign materialfrom workpieces.

BACKGROUND OF THE INVENTION

[0003] Many items, such as tools, automobile parts, fixtures, etc., havea metal structure that is combined with comparatively less durable partsor materials, such as coatings, gaskets, fiberglass, enamels, paints,etc. In general, the less durable parts or materials in such itemsdeteriorate more quickly than the metal structures that they arecombined with. Rather than discarding an item when the less durableparts or materials deteriorate, the metal structure of the item can besalvaged by removing the deteriorated material.

[0004] A conventional device for removing material from a metalstructure is disclosed in U.S. Pat. No. 3,830,196 to Guttman et al. InFIG. 1, Guttman discloses a stationary painting line in which parts arehung from aluminum hangers 40, and advanced through a painting zone 20by a conveyor 10. The painting line includes a burn-off oven 28 forremoving paint that has accumulated on the aluminum hangers 40.Guttman's painting line is a static structure, and occupies a largespace. In addition, workers located near the painting line may beexposed to harmful combustion products produced in the burn-off oven 28.

[0005] U.S. Pat. No. 4,270,898 to Kelly discloses a conventional burnercontrol method for removing materials from metal parts 5 in areclamation furnace 1. Kelly's reclamation furnace 1 is also a staticstructure, and the parts 5 must therefore be brought to the furnace 1for processing. In addition, workers located near the furnace 1 may beexposed to harmful combustion products.

SUMMARY OF THE INVENTION

[0006] The present invention is in part directed to providing a mobilefurnace that can be transported to a worksite for facilitating theremoval of material from workpieces at the worksite. The invention isalso directed to a method for facilitating the removal of foreignmaterials from workpieces at a worksite, using a mobile furnace.

[0007] According to one embodiment of the present invention, a mobilefurnace comprises a wheeled vehicle, such as a trailer, for transportingthe mobile furnace to a worksite, and burners for heating a combustionchamber to a temperature sufficient to facilitate removal of foreignmaterial from workpieces placed in the combustion chamber. Because it ismobile, the mobile furnace does not require a fixed area for operation.The worksite can therefore be utilized for other purposes after materialremoval is completed.

[0008] The mobile furnace according to the present invention can also beoperated at a remote worksite, so that workers and other persons are notexposed to combustion products produced during operation of the mobilefurnace.

[0009] According to another embodiment of the present invention, amobile furnace is used in a method to facilitate removal of foreignmaterial from workpieces. In the method, workpieces are placed in themobile furnace and heated to a temperature sufficient to remove foreignmaterial from the workpieces (generally, the workpieces are“processed”). The burned foreign material, or ash, can be retained inthe mobile furnace after removal from the workpieces, and transported toanother site for disposal, or for further processing.

[0010] According to the method, the worksite receives minimal exposureto the ash produced during processing of the workpieces.

[0011] Further scope of applicability of the present invention willbecome apparent from the detailed description given hereinafter.However, it should be understood that the detailed description andspecific examples, while indicating preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURES

[0012] The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

[0013]FIG. 1 is a perspective view of a mobile furnace according to oneembodiment of the present invention;

[0014]FIG. 2 is a front view of a mobile furnace according to oneembodiment of the present invention;

[0015]FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

[0016]FIG. 4 is a sectional view of the shell of the mobile furnace,taken along line 44 in FIG. 3; and

[0017]FIG. 5 is a perspective view of a process basket according to oneembodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018]FIG. 1 is a perspective view of a mobile furnace 10 according toan embodiment of the present invention. The mobile furnace 10 comprisesa shell 20, two burners 50 (only one burner 50 is shown in FIG. 1), aburner control 60, an opening/closing device 90, and a trailer 40.

[0019] The shell 20 comprises a shell body 21 and a cover 22. The cover22 may be pivotably attached to the shell body 21 by one or more hinges23 (see FIG. 3). When the cover 22 is closed, an opening edge 24 of thecover 22 abuts with an opening edge 26 of the shell body 21 to form agenerally cylindrical shell 20. The shell 20 may be made from a mildsteel, such as 12 gauge mild steel, and may be formed by separating a550 gallon oil barrel into the shell body 21 and the cover 22.

[0020] The trailer 40 comprises a frame 42 supported on wheels 44, ahitch 46, and a catwalk 48 extending along a side of the frame 42. Thetrailer 40 may be of a conventional design. For example, in theexemplary embodiment of FIG. 1, the trailer 40 is a ½ ton trailer. Foursupport members 49 (only one is visible in FIG. 1) connect the shell 20to the trailer 40. Alternatively, wheels may be provided directly onshell 20.

[0021]FIG. 2 is a front view of the mobile furnace 10 shown in FIG. 1.In FIG. 2, two burner covers 28 are attached to the shell body 21, oneburner cover 28 being attached to each end of the shell body 21. In FIG.1, the mobile furnace 10 is illustrated with the burner covers 28removed. The burner covers 28 are attached to the shell body 21 toprotect the burners 50, and to prevent a person from contacting theburners 50. The burner covers 28 may be attached to the shell body 21,for example, at flanges 30 by, for example, screws, a bolt attachment,or welds.

[0022] The burners 50 (and the burner covers 28) are illustrated asbeing attached to each end of the shell 20, however, the burners 50 maybe attached at other locations on the shell 20. The figures illustratethe mobile furnace 10 as having two burners 50, however, varying numbersof burners can be used in the mobile furnace 10. The burners 50 may beattached to the shell body 21 by, for example, a bolt attachment,screws, or welds. Each burner 50 communicates with the interior of theshell 20 via an aperture (not shown) in the end of the shell body 21 towhich it is attached. The interior of the shell 20 defines a combustionchamber 34 that will be discussed later with reference to FIGS. 3 and 4.

[0023] The burners 50 may be, for example, oil burners, such as thoseused in residential heating systems. For example, the burners 50 may be85,000 Btu diesel fuel burners. It is advantageous to use conventionaloil burners because they burn inexpensive, easy to obtain, diesel fuel.In addition, the electrical power required to run conventional oilburners can be supplied by a standard 110 V AC current source. A burner50 requires electrical current to drive elements such as a fan, a pump,and an igniter transformer, which may all be a part of the burner 50.

[0024] The burner control 60 controls the operation of the burners 50,and is electrically connected to the burners 50 via cabling disposedwithin a conduit 62. The burner control 60 may have a manual ON/OFFswitch for activating/deactivating the burners 50. In addition, theburner control 60 can include an electronic memory for controlling thetime that the burners 50 operate, and for controlling the thermal outputof the burners 50.

[0025] The AC current required to operate the burners 50 is suppliedfrom the burner control 60 to the burners 50 via the cabling in theconduit 62. The burner control 60 can in turn be supplied with ACcurrent from a standard 110 V AC power source. The standard 110 V ACpower source can be external to the mobile furnace 10, such as astationary 110 V AC power outlet, or it may be onboard the mobilefurnace 10, such as a mobile power generator. Other power sources can beused to supply the burner control 60, provided that the current isadjusted to be suitable for use by the burners 50.

[0026] A conduit section 64 extends downwardly from the burner control60, and is connected to conduit sections 66. The cabling within theconduit 62 conducts current to each of the burners 50 through arespective conduit section 66. The burner control 60 controls theburners 50 by selectively opening and closing a switch, such as a relay,between the AC current supply at the burner control 60 and each burner50.

[0027] The burner control 60 can operate the burners 50 as a function ofboth the time that workpieces are held in the combustion chamber 34during operation of the burners 50, and the temperature in thecombustion chamber 34. The temperature of the combustion chamber 34 iscommunicated to the burner control 60 from a temperature sensor 63 (seeFIGS. 3 and 4) located in the combustion chamber 34. The temperaturesensor 63 may be, for example, a thermocouple.

[0028] One or more exhaust pipes 32 are located on an upper surface ofthe cover 22, for exhausting combustion gases from the combustionchamber 34. The number and size of the exhaust pipes 32 utilized in themobile furnace 10 is dependent upon the output of the burners 50. Whilefour exhaust pipes 32 are shown for the purposes of illustration, alesser or greater number of exhaust pipes 32 may be used.

[0029] The structure of the mobile furnace will now be discussed withreference to FIGS. 3 and 4. FIG. 3 is a sectional view of the mobilefurnace 10, taken along line 3-3 in FIG. 2. FIG. 4 is a sectional viewof the shell body 21, taken along line 4-4 in FIG. 3.

[0030] Each burner 50 includes a burner head 55 that extends, through anaperture 36, into the combustion chamber 34. A process basket 110 isprovided in the combustion chamber 34 for supporting workpieces in thecombustion chamber 34. The process basket 110 has support portions 115located at either end of the process basket 110 (see FIG. 5), and eachsupport portion 115 is pivotably supported by trunnions (not shown)located on an upper portion of the interior of the cover 22. When thecover 22 is pivoted about the hinges 23, the process basket 110 islifted within the interior of the shell body 21, allowing easy access toworkpieces supported in the process basket 110.

[0031] As an alternative to a process basket 110, workpieces can besupported in the combustion chamber 34 on a rack disposed in the shellbody 21, for example, or, the workpieces can simply be placed in thebottom of the shell body 21.

[0032] Both the shell body 21 and the cover 22, which define thecombustion chamber 34, are lined with insulation 70. The insulation 70includes, for example, a first insulation layer 72, a second insulationlayer 74 disposed over the first insulation layer 72, and a ceramiclayer 75 disposed over the second insulation layer 74. The insulation 70retards the escape of heat generated by the burners 50 during operationof the mobile furnace 10. The insulation 70 therefore increases theefficiency of the mobile furnace 10, because the burners 50 can burnless fuel in heating the combustion chamber 34 to a desired processingtemperature.

[0033] In addition, the insulation 70 prevents the exterior of the shell20 from becoming excessively hot during operation of the mobile furnace10. Even when the combustion chamber 34 is at a normal processingtemperature, which may exceed 1200° F., an operator usually can safelytouch the exterior of the shell 20.

[0034] The insulation 70 is illustrated as comprising two layers.However, a single layer, or three or more layers of insulation maycomprise the insulation 70. The first insulation layer 72 and the secondinsulation layer 74 may be, for example, conventional refractoryblankets made from Al—O (47-48% by weight) and Si—O (51-52% by weight).Refractory blankets of this type are typically rated to withstandtemperatures of up to 2,400° F.

[0035] The ceramic layer 75 may be a fritted glaze coating, which is acomposite of frits and glaze. A glaze may be, for example, a silicaglass, and frits may be particulate minerals, metals, or combinationsthereof, which may be added to a glaze to adjust, for example, the meltcharacteristics of the glaze. The amount of frits added to the glazedetermines the temperature at which the fritted glaze melts, and thefritted glaze used to form the ceramic layer 75 in the mobile furnace 10is formed such that it remains solid over an expected range ofprocessing temperatures for the combustion chamber 34. The ceramic layer75 is rigid, and serves to protect the relatively fragile firstinsulation layer 72 and the second insulation layer 74 from cracking orfracture. This ceramic layer 75 is important because the firstinsulation layer 72 and the second insulation layer 74 may be subjectedto stresses during transport of the mobile furnace 10.

[0036] The insulation 70 lining the shell body 21 is secured to theinterior of the shell body 21 if necessary by a retaining grid 82.Channel 80 extends along the opening edge 26 of the shell body 21, andcomprises a series of elongated metal members having generally U-shapedcross sections. The edges of the insulation 70 located near the openingedge 26 are located within the U-shaped cross sections of the channel80. The channel 80 can be attached to the shell body 21 by welding,bolts, screws, etc.

[0037] The retaining grid 82 is a wire mesh that conforms to the shapeof the combustion chamber 34. In the shell body 21, edges of theretaining grid 82 are disposed in the channel 80, along with theinsulation 70. The retaining grid 82 helps to secure the insulation 70against the interior of the shell body 21.

[0038] The insulation 70 lining the cover 22 is secured to the cover 22if necessary by the retaining grid 82. Channel 78 extends along theopening edge 24 of the cover 22, and edges of the insulation 70 near theopening edge 24 are disposed within the channel 78. The edges of theretaining grid 82 near the opening edge 24 are disposed in the channel78 along with the insulation 70. The retaining grid 82 helps to securethe insulation 70 against the interior of the cover 22.

[0039] If necessary, an opening/closing device 90 is provided foropening and closing the cover 22. The opening/closing device 90 includesa winch 92 mounted on the frame 42, a lifting arm 94 mounted on thecover, and a cable 96 connected at one end to the winch 92, looped overa hook 97 suspended from the lifting arm 94, and secured to the frame 42at an anchor 98. The winch 92 may be powered by a 100 V AC power source.As an alternative to the winch 92, a manual crank can be connected tothe cable 96 for opening and closing the cover 22.

[0040] The operation of the mobile furnace 10 will now be discussed.

[0041] When an operator of the mobile furnace 10 determines a worksitefor removing foreign material from workpieces, the mobile furnace 10 ismoved to the worksite. At the worksite, the cover 22 is raised byactivating the opening/closing device 90. Workpieces are then loadedinto the process basket 110 for processing, and the cover 22 is loweredby the opening/closing device 90.

[0042] Once the cover 22 is closed, the operator activates the burners50 at the burner control panel 60. The operator can manually close aswitch to provide AC power to the burners 50. Alternatively, theoperator can initiate a preselected process sequence for the burners 50,the sequence being stored in a memory of the burner control 60.

[0043] Upon activation, the burners 50 propel ignited fuel into thecombustion chamber 34, heating the combustion chamber 34 to a processingtemperature sufficient to facilitate the removal of foreign materialfrom workpieces in the process basket 110. The processing temperatureshould be high enough to facilitate removal of foreign materialassociated with a workpiece, but not so high as to warp or melt theworkpiece. For example, a processing temperature of at least 400° F. isapplicable for facilitating the removal many paints, lacquers, etc. fromworkpieces. A processing temperature exceeding about 700° F. ispreferable because it allows for the removal of materials having highercombustion temperatures. In addition, processing workpieces at higherthan 700° F. is faster than processing at lower temperatures.

[0044] When the workpieces in the combustion chamber 34 have beenexposed to the processing temperature of the combustion chamber 34 for apredetermined amount of time, the burner controller 60 ceases the flowof current to the burners 50. The burners 50 then shut off, and ignitedfuel is no longer supplied to the combustion chamber 34. The cover 22 isthen raised, and the workpieces are removed from the process basket 110.

[0045] If present on the workpieces, ash from the burned foreignmaterial is removed from the workpieces after the burners 50 aredeactivated. The ash may be removed while the workpieces are suspendedover the shell body 21, so that no ash from the workpieces is left atthe worksite.

[0046] After the ash is removed from the workpieces, the parts areremoved from the process basket 110. The cover 22 is then closed and themobile furnace 10 is transported to another location for disposal of, orfor further processing of, the ash produced from the processing of theworkpieces. Therefore, the worksite receives minimal exposure to the ashgenerated by processing workpieces in the mobile furnace 10.

[0047] The invention being thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A method for facilitating removal of foreignmaterial associated with workpieces using a mobile furnace, the methodcomprising: moving the mobile furnace to a first location; and heating aworkpiece in the furnace for a time period and at a temperaturesufficient to facilitate removal of foreign material associated with theworkpiece.
 2. The method of claim 1, wherein the temperature is at least700° F.
 3. The method of claim 1, wherein heating a workpiece in themobile furnace includes placing the workpiece on a support deviceoperatively connected to a cover of the furnace.
 4. The method of claim1, further comprising: removing the workpiece from the furnace; andtransporting foreign material burned in the furnace to a secondlocation.